Although insecticidal agents and compositions have been developed to control insect pests such as agrohorticultural pests or hygienic pests, and in practice have been used as a single or a mixed agent, economically efficient and ecologically safe insect control compositions are still being sought. Insecticidal compositions which allow for reduced effective dosage rates, increased environmental safety and lower the incidence of insect resistance are highly desirable. The rotational application of insect control agents having different modes of action may be adopted for good pest management practice, however, this approach does not necessarily give satisfactory insect control. Combinations of insect control agents have been studied, however, a high synergistic action has not always been found. Obtaining an insecticidal composition which demonstrates no cross-resistance to existing insecticidal agents, no toxicity problems and little negative impact on the environment is extremely difficult.
Therefore, it is an object of this invention to provide a synergistic insecticidal composition which demonstrates a high controlling effect with concomittant reduced crop production cost and reduced environmental load.
It is another object of this invention to provide methods for synergistic insect control and enhanced crop protection.
The present invention provides a synergistic insecticidal composition comprising as essential active ingredients a synergistically effective amount of a neuronal sodium channel antagonist and an arylpyrrole insecticide.
The present invention also provides a method for synergistic insect control which comprises contacting said insect with a synergistically effective amount of a combination of a neuronal sodium channel antagonist and an arylpyrrole insecticide.
The present invention further provides a method for the enhanced protection of plants from infestation and attack by insects.
When two or more substances in combination demonstrate unexpectedly high biological activity, for example, insecticidal activity, the resulting phenomenon may be referred to as synergism. The mechanism of synergism is not fully understood, and quite possibly may differ with different combinations. However, the term synergism, as used in this application designates a cooperative action encountered in a combination of two or more biologically active components in which the combined activity of the two or more components exceeds the sum of the activity of each component alone.
Surprisingly, it has now been found that a composition which comprises a combination of a neuronal sodium channel antagonist and an arylpyrrole insecticide provides superior insect control at lower levels of the combined active agents than may be achieved when the neuronal sodium channel antagonist or the arylpyrrole insecticide is applied alone.
As used in this application, the term neuronal sodium channel antagonist designates a compound which is capable of preventing the ability of a neuron cell to transfer sodium ions across the cell membrane. A neuron cell thus affected is unable to fire, resulting in paralysis, and ultimately mortality, in the target host. Descriptions of neuronal sodium channel antagonists and their mode of action may be found in Pesticide Biochemistry and Physiology, 60: 177-185 or Archives of Insect Biochemistry and Physiology, 37: 91-103, both of which are hereby incorporated by reference.
Neuronal sodium channel antagonists include compounds such as those described in U.S. Pat. Nos. 5,543,573; 5,708,170; 5,324,837 and 5,462,938, among other publications. Exemplary of the neuronal sodium channel antagonist compounds useful in the composition of this invention are those compounds having the structural formula 
wherein
A is CR4R5 or NR6;
W is O or S;
X, Y, Z, Xxe2x80x2, Yxe2x80x2 and Zxe2x80x2 are each independently H; halogen; OH; CN; NO2; C1-C6alkyl optionally substituted with one or more halogen, C1-C3alkoxy, C1-C3haloalkoxy, C3-C6cycloalkyl, C2-C6alkenyloxy or sulfonyloxy groups;
C1-C6alkoxy optionally substituted with one or more halogen, C1-C3alkoxy or C3-C6cycloalkyl groups;
C1-C6alkoxycarbonyl, C3-C6cycloalkylcarbonyloxy, phenyl optionally substituted with one or more halogen, C1-C4alkyl, or C1-C4alkoxy groups;
aminocarbonyloxy optionally substituted with one or more C1-C3alkyl groups;
C1-C6alkoxycarbonyloxy; C1-C6alkylsulfonyloxy;
C2-C6alkenyl; or NR12R13;
m, p and q are each independently an integer of 1, 2, 3, 4, or 5;
n is an integer of 0, 1 or 2;
r is an integer of 1 or 2;
t is an integer of 1, 2, 3 or 4;
R, R1, R2, R3, R4 and R5 are each independently H or C1-C4alkyl;
R6 is H, C1-C6alkyl, C1-C6haloalkyl, C1-C6alkoxyalkyl, C1-C6alkoxy, C1-C6haloalkoxy, C2-C6alkenyl, C2-C6alkynyl, C1-C6alkylcarbonyl, C1-C6alkoxycarbonyl, C1-C6alkylthio, or C1-C6haloalkylthio;
R7 and R8 are each independently H; halogen; C1-C6alkyl; C1-C6alkylcarbonyloxy; or phenyl optionally substituted with one or more halogen, CN, NO2, C1-C6alkyl, C2-C6haloalkyl, C1-C6alkoxy or C1-C6haloalkoxy groups;
R9 and R10 are each independently H, or C1-C4alkyl;
R11 is H, C1-C6alkyl, C1-C6haloalkyl, C1-C4alkylcarbonyl, C1-C6alkoxycarbonyl, or C1-C6haloalkoxycarbonyl;
R12 and R13 are each independently H or C1-C6alkyl;
G is H; C1-C6alkyl optionally substituted with one or more halogen, C1-C4alkoxy, C1-C6haloalkoxy, CN, NO2S(O)uR14, COR15, CO2R16, phenyl or C3-C6cycloalkyl groups;
C1-C6alkoxy; C1-C6haloalkoxy; CN; NO2; S(O)uR17; COR18; CO2R19; phenyl optionally substituted with one or more halogen, CN, C1-C3haloalkyl, or C1-C3haloalkoxy groups;
C3-C6cycloalkyl; or phenylthio;
Q is phenyl optionally substituted with one or more halogen, CN, SCN, NO2, S(O)uR20, C1-C4alkyl, C1-C4haloalkyl, C1-C4alkoxyalkyl, C1-C6alkoxy, C1-C6haloalkoxy, or NR21R22 groups;
u is an integer of 0, 1 or 2;
R14, R15, R16, R18, R19, R21 and R22 are each independently H or C1-C6alkyl;
R17 and R20 are each independently C1-C6alkyl or C1-C6haloalkyl;
R33 is CO2R34;
R34 is H, C1-C6alkyl, C1-C6haloalkyl, phenyl or halophenyl; and the dotted line configuration
 represents a double bond or a single bond (i.e. Cxe2x80x94N or Cxe2x95x90N); or
a stereoisomer thereof.
Preferred neuronal sodium channel antagonists suitable for use in the composition of the invention are those compounds of formula I, II or III wherein the dotted line configuration  represents a double bond.
More preferred neuronal sodium channel antagonists suitable for use in the inventive composition are those compounds of formula I or formula III wherein the dotted line configuration represents a double bond.
Particularly preferred neuronal sodium channel antagonists useful in the composition of the invention are those compounds of formula I or formula III wherein W is O; X is trifluoromethoxy and is in the 4-position; Y is trifluoromethyl and is in the 3-position; Z is CN and is in the 4-position; A is CH2; n is 0; m, p and q are each 1; R and R1 are each H; Zxe2x80x2 is Cl; R33 and G are each CO2CH3; Q is p-(trifluoromethoxy)phenyl; and the dotted line configuration  represents a double bond; or a stereoisomer thereof.
Further neuronal sodium channel antagonist compounds include those described in U.S. Pat. Nos. 5,116,850 and 5,304,573, among other publications. Exemplary of further neuronal sodium channel antagonist compounds suitable for use in the composition of the invention are those compounds having structural formula 
wherein
W is O or S;
Xxe2x80x3 and Yxe2x80x3 are each independently H; halogen; CN; SCN; C1-C6alkyl optionally substituted with one or more halogen, NO2, CN, C1-C4alkoxy, C1-C4alkylthio, phenyl, halophenyl, C1-C4alkylsulfonyl, C1-C4haloalkylsulfonyl, or C1-C4alkoxycarbonyl groups;
C2-C4alkenyl; C2-C4haloalkenyl; C2-C4alkynyl; C2-C4haloalkynyl; C3-C6cycloalkyl; C3-C6halocycloalkyl; phenyl optionally substituted with one or more halogen, CN, NO2, C1-C4alkyl, C1-C4haloalkyl, C1-C4alkoxy, C1-C4haloalkoxy, C1-C4alkylthio, C1-C4alkylsulfonyl or C1-C4haloalkylsulfonyl groups;
C1-C4alkylcarbonyl; C1-C4haloalkylcarbonyl; or
NR28R29;
m is an integer of 1, 2, 3, 4, or 5;
Gxe2x80x2 is phenyl optionally substituted with one or more groups which may be the same or different selected from Xxe2x80x3;
a 5-membered heteroaromatic ring containing one or two heteroatoms selected from 0 or 1 oxygen, 0 or 1 sulfur and 0, 1 or 2 nitrogen atoms said 5-membered heteroaromatic ring being attached via carbon and being optionally substituted with one or more groups which may be the same or different selected from Xxe2x80x3; or
a 6-membered heteroaromatic ring containing one or two heteroatoms selected from 0 or 1 oxygen, 0 or 1 sulfur and 0, 1 or 2 nitrogen atoms said 6-membered heteroaromatic ring being attached via carbon and being optionally substituted with one or more groups which may be the same or different selected from Xxe2x80x3;
Qxe2x80x2 is H; C1-C6alkyl optionally substituted with one or more halogen, CN, C1-C3alkoxy, C1-C6alkoxycarbonyl, or phenyl optionally substituted with one or more halogen, CN, NO2, C1-C4alkyl, C1-C4haloalkyl, C1-C4alkylsulfonyl or C1-C4alkylsulfinyl groups;
C2-C6alkenyl; C2-C6alkynyl; or phenyl optionally substituted with one to three groups, which may be the same or different, selected from Xxe2x80x3;
R23, R24, R25, R26, R27, R28 and R29 are each independently H or C1-C4alkyl; and the dotted line configuration  represents a double bond or a single bond (i.e. Cxe2x80x94N or Cxe2x95x90N); or
a stereoisomer thereof.
Further preferred neuronal sodium channel antagonist compounds of the invention are those compounds of formula IV or V wherein the dotted line configuration  represents a double bond.
Other preferred neuronal sodium channel antagonist compounds suitable for use in the composition of the invention are those compounds of formula IV or V wherein W is O; Xxe2x80x3 and Yxe2x80x3 are each independently H or C1-C6haloalkyl; m is 1; R23, R24, R25, R26 and R27 are each H; G is phenyl optionally substituted with one or more halogen atoms; Qxe2x80x2 is halophenyl or C1-C4alkyl optionally substituted with one phenyl or halophenyl group; and the dotted line configuration  represents a double bond; or a stereoisomer thereof.
Arylpyrrole insecticides include those described in U.S. Pat. Nos. 5,010,098; 5,492,925; 5,484,807 and 5,284,863, among other publications. Exemplary of the arylpyrrole insecticides suitable for use in the composition of the invention are those arylpyrroles having the structural formula 
Hal is Cl or Br;
x is an integer of 1, 2, 3, 4, 5 or 6;
D is H; C1-C6alkyl optionally substituted with one or more halogen, CN, OH, C1-C4alkoxy, C1-C4haloalkoxy, C1-C5alkylthio, C1-C4alkylcarbonyloxy, C1-C4haloalkylthio, C1-C6alkenylcarbonyloxy, phenylcarbonyloxy, halophenylcarbonyloxy, phenoxy, halophenoxy, phenyl, halophenyl or C1-C3alkylphenyl groups,
C2-C6alkenyl; C2-C6haloalkenyl; CN; C2-C6alkynyl; C2-C6haloalkynyl; di-(C1-C4alkyl)aminocarbonyl; or C3-C6polymethyleneiminocarbonyl;
L is H or halogen;
M and Mxe2x80x2 are each independently H, halogen, CN, NO2, C1-C4alkyl, C1-C4haloalkyl, C1-C4alkoxy, C1-C4haloalkoxy, C1-C4alkylthio, C1-C4haloalkylthio, C1-C4alkylsufonyl, C1-C4haloalkylsulfonyl, C1-C4alkylcarbonyl, C1-C4haloalkylcarbonyl, NR35R36 or when M and M1 are attached to adjacent carbon atoms, they may be taken together with the carbon atoms to which they are attached to form a ring in which MM1 represents xe2x80x94OCH2Oxe2x80x94, xe2x80x94OCF2Oxe2x80x94 or xe2x80x94CHxe2x95x90CHxe2x80x94CHxe2x95x90CHxe2x80x94;
Axe2x80x2 is O or S;
R30, R31 and R32 are each independently hydrogen, halogen, NO2, CHO or R31 and R32 may be taken together with the carbon atoms to which they are attached to form a ring in which R31R32 represent 
Lxe2x80x2, Lxe2x80x3, T and V are each independently H, halogen, CN or NO2 with the proviso that no more than two of Lxe2x80x2, Lxe2x80x3, T or V are NO2; and
R35 and R36 are each independently H or C1-C4alkyl.
Preferred arylpyrroles suitable for use as one essential active ingredient in the composition of the invention are those arylpyrroles of formula VI wherein D is H or ethoxymethyl; Ar is phenyl substituted with one or more halogen or halomethyl groups; and n is 1.
Preferred embodiments of the invention are those having a neuronal sodium channel antagonist compound of formula I or formula III and an arylpyrrole compound of formula VI as active ingredients.
More preferred embodiments of the invention are those having a formula I or formula III compound wherein W is O; X is trifluoromethoxy and is in the 4-position; Y is trifluoromethyl and is in the 3-position; Z is CN and is in the 4-position; A is CH3; n is 0; m, p and q are each independently 1; R and R1 are each independently H; Z is Cl;, R33 and G are each independently CO2CH3; Q is p-(trifluoromethoxy)phenyl; and the dotted line configuration  represents a double bond and a formula VI arylpyrrole wherein D is H or ethoxymethyl; Ar is phenyl substituted with one or more halogen or halomethyl groups; and x is 1.
Particularly preferred embodiments of the invention are those having as the active ingredients a compound of formula I or III wherein W is O; X is trifluoromethoxy and is in the 4-position; Y is trifluoromethyl and is in the 3-position; Z is CN and is in the 4-position; A is CH3; n is 0; m, p and q are each 1; R and R1 are each H; Zxe2x80x2 is Cl;, R33 and G are each CO2CH3; and Q is p-(trifluoromethoxy)phenyl, and the dotted line configuration  represents a double bond and an arylpyrrole of formula VI wherein D is H or ethoxymethyl; Ar is p-chlorophenyl or 3,5-dichlorophenyl; and x is 1.
In the specification and claims the term haloalkyl designates an alkyl group CxH2x+1 having 1 to 2x+1 halogen atoms which may be the same or different. Similarly, the terms haloalkenyl, haloalkynyl, haloalkoxy, halophenyl and the like designate mono- to perhalogen substitution wherein the halogens may be the same or different. Halogen designates Cl, Br, I or F.
Each of the compounds of formula I, II, III, IV and V embody assymetric centers which may be represented in the stereoisomeric R-form or S-form. The present invention also includes the R-form, the S-form or mixtures comprising the R-form and the S-form in any ratio. For compounds of formula III, the S-form is preferred.
Advantageously, the neuronal sodium-channel antagonist compound of formula I, II, III, IV or V or a mixture thereof may be formulated with an arylpyrrole insecticide. Said formulation may then be dispersed in a solid or liquid diluent for application to the insect, its food supply, breeding ground or habitat as a dilute spray or as a solid dust or dust concentrate. Customary formulation adjuvants as well as additional agriculturally acceptable active ingredients may be added and are within the scope of the invention.
The active ingredients of the inventive composition may also be formulated separately as a wettable powder, emulsifiable concentrate, aqueous or liquid flowable, suspension concentrate or any one of the conventional formulations used for insect control agents and tank mixed in the field with water or other inexpensive liquid for application as a liquid spray mixture. The separately formulated compositions may also be applied sequentially.
In actual practice, the composition of the invention is applied to the plant foliage or plant stem or insect habitat as a dilute spray prepared from any of the above-said formulations. In practice it has been found that the active ingredients of the composition of the invention are highly synergistic when present at a ratio of neuronal sodium channel antagonist compound to arylpyrrole insecticide of about 1:10 to 1:50.
The compositions of the invention are superior insecticidal compositions and are especially useful for protecting growing and harvested plants including: leguminous crops such as soybeans, snap beans, peas, wax beans and the like as well as cotton, forage crops, cole crops, leafy vegetables, tobacco, hops, tomatoes, potatoes, flowering ornamentals such as chrysanthemums, vine crops such as grapes, squash, pumpkin or melon and fruit trees such as cherry, peach, apple or citrus, from the ravages of insects.
The synergistic insecticidal composition of the invention is found to be highly active against a wide variety of lepidopteran and coleopteran insects such as Helicoverpa zea (cotton bollworm), Heliothis virescens (tobacco budworm), Leptinotarsa decemlineata (Colorado potato beetle), Diabrotica spp. (corn rootworm) and the like.
Further, the composition of the invention may be useful in the prevention and control of public health pests such as houseflies, mosquitoes, cockroaches, ants, termites or the like.
These and other advantages of the invention may become more apparent from the examples set forth herein below. These examples are provided merely as illustrations of the invention and are not intended to be construed as a limitation thereof.